Hundreds of thousands of out-of-work Americans are receiving their final unemployment checks sooner than they expected, even though Congress renewed extended benefits until the end of the year. The checks are stopping for the people who have the most difficulty finding work: the long-term unemployed. More than five million people have been out of work for longer than half a year. Federal benefit extensions, which supplemented state funds for payments up to 99 weeks, were intended to tide over the unemployed until the job market improved.